FR3137366A1 - Attraction device - Google Patents

Abstract

Rigging device The invention relates to a rigging system for supporting a naval vessel in dry dock, comprising at least one tin (1) comprising a lower support element (2) resting on a floor (6) and an upper support element (4) intended to support the naval vessel in a direction of elevation (Z), said tin (1) comprising at least one lower suspension device (8) and at least one upper suspension device (16 ), said lower support element (2) resting on the ground (6) via said lower suspension device (8) arranged to absorb external stresses on the tin (1) in directions substantially perpendicular to the direction d elevation (Z) and said upper support element (4) resting on the lower support element (2) via said upper suspension device (16) arranged to absorb the stresses on the tin (1) according to the elevation direction (Z). Figure for abstract: 1

Description

Attraction device

The present invention relates to a securing system for supporting a naval vessel in dry dock.

Such a securing system makes it possible to support a naval vessel before it is launched or during maintenance operations during which the naval vessel must be kept out of the water.

In known manner, such a securing system comprises a plurality of tins resting on the ground and distributed under the hull of the naval vessel, each tin being adapted to support a part of the hull of the naval vessel in a direction of elevation.

Each tin must therefore be sized to support a heavy load. However, in the event of seismic activity, for example during an earthquake, the tins propagate the effects of this activity to the supported naval vessel, which entails risks of damage to equipment on board the naval vessel. This risk can be increased in the case of military naval vessels, particularly stealth ones, in which acoustic filtration pads can be added in order to reinforce their acoustic discretion. Indeed, such studs tend to amplify the phenomenon of propagation of the effects of seismic activity in naval vessels which are equipped with them.

In order to reduce the risk of damage, the equipment of the naval vessel, in particular those which present particular safety issues, for example in the case of a nuclear-powered vessel, must be arranged to withstand the stresses due to propagation seismic activity. Such an arrangement represents a significant additional cost and increases the complexity of the equipment, without providing any particular advantage to the naval vessel when it is launched. Furthermore, in order to be effective, this particular arrangement must be tested, which further increases the costs associated with it.

One of the aims of the invention is to overcome these drawbacks by proposing a coupling system making it possible to reduce the transmission of seismic activity to the naval vessel supported by the coupling system.

To this end, the invention relates to a rigging system for supporting a naval vessel in dry dock, comprising at least one tin comprising a lower support element resting on a ground and an upper support element intended to support the naval building in a direction of elevation, said tin comprising at least one lower suspension device and at least one upper suspension device, said lower support element resting on the ground via said lower suspension device arranged to absorb shocks external stresses on the tin in directions substantially perpendicular to the direction of elevation and said upper support element resting on the lower support element via said upper suspension device arranged to absorb the stresses on the tin in the direction elevation.

The lower and upper suspension devices make it possible to absorb external stresses exerted on the tin, particularly in the event of seismic activity, so that these stresses are not transmitted, or at least transmitted in a reduced manner, to the naval vessel supported by this tin. Thus, the risks of damage to the naval vessel's equipment are greatly reduced and it is not necessary to provide a particular arrangement of the equipment on board the naval vessel to resist the effects of seismic activity. The lower and upper suspension devices can in particular be arranged so that the stresses transmitted to the naval vessel are less than or equal to those which are transmitted in the event of seismic activity to the naval vessel when it is in the water. Thus, the arrangement of the equipment which is designed to resist seismic activity when the naval vessel is in the water is sufficient to allow this equipment to also resist when the naval vessel is in dry dock.

The coupling system according to the invention may also comprise one or more of the following characteristics, taken individually or in any technically conceivable combination:

- the lower suspension device comprises at least one lower suspension element extending along an axis extending in the direction of elevation;

- the lower suspension element comprises a central lead cylinder surrounded by an elastomeric material, said central cylinder extending along the axis extending in the direction of elevation;

- the elastomeric material comprises a plurality of layers of elastomeric material stacked on top of each other in the direction of elevation, said layers being reinforced by steel hoops;

- the lower suspension device comprises several lower suspension elements distributed under a lower surface of the lower support element, said lower surface extending substantially parallel to the ground and facing said ground;

- the upper suspension device comprises at least two upper suspension elements, extending on either side of the upper support element in a transverse direction substantially perpendicular to the direction of elevation, said upper suspension elements being inclined towards each other and each extending along an inclined axis forming a non-zero angle with the direction of elevation;

- the angle between the inclined axis of each upper suspension element and the direction of elevation is substantially between 105° and 125°;

- each upper suspension element is an insulator made of high damping elastomeric material;

- the upper suspension device comprises a plurality of pairs of upper suspension elements, said pairs being adjacent to each other in a longitudinal direction substantially perpendicular to the direction of elevation and to the transverse direction; And

- the coupling system comprises a plurality of tins spaced from each other at least in a main direction of the naval vessel to be supported by the coupling system.

Other aspects and advantages of the invention will appear on reading the description which follows, given by way of example and made with reference to the appended drawings, in which:

- there is a schematic perspective representation of a pin of a coupling system according to the invention,

- there is a schematic cross-sectional representation of the tin of the , the suspension devices being represented schematically, and

- there is a schematic perspective representation with a broken part of a lower suspension element used in a tin of a coupling system according to the invention.

With reference to Figs. 1 and 2, we describe a tin 1 of a rigging system for the support of a naval vessel in dry dock. In known manner, such a rigging system 1 comprises a plurality of tins 1 distributed under the hull of a naval vessel in order to support it when it is out of the water, for example before it is launched. water or during maintenance operations requiring the naval vessel to be removed from the water. For a slender naval vessel extending mainly in a main direction corresponding to the front-to-back direction of the naval vessel, the tins 1 are for example spaced apart from each other in this main direction. It is understood that several rows of tins can be provided so as to support the entire hull of the naval vessel and keep it clear of the ground. The invention applies to any type of naval vessel, whether a surface vessel or a submersible vessel. The particular characteristics of the pins of the coupling system according to the invention being the same for all pins 1, only one of these will now be described.

The tin 1 comprises a lower support element 2 and an upper support element 4. The tin 1 rises in an elevation direction Z, corresponding to the vertical direction when the tin 1 rests on a horizontal ground 6. In other words, the direction of elevation Z is substantially perpendicular to the ground 6. In the description, the terms "height", "lower" and "upper", "above", "below" are defined by relative to the direction of elevation Z.

The lower support element 2 rests on the ground 6, for example formed by the ground of the place where the naval vessel to be supported is placed in dry dock or by a support placed on this ground, such as a raft. The lower support element 2 rests more particularly on the ground via a lower suspension device 8, which will be described in more detail later. By this we mean that the lower suspension device 8 is interposed between the lower support element 2 and the ground 6 so that external stresses passing through the ground 6 pass through the lower suspension device 8 before reaching the lower support element 2 and so that there is no direct transmission of these stresses from the ground to the lower support element 2

The lower support element 2 comprises a lower surface 10, facing the ground 6 and resting on the lower suspension device 8, and an upper surface 12, facing the upper support element 4. The lower surface 10 and the upper surface 12 are spaced apart from each other in the direction of elevation Z.

The lower surface 10 is arranged to receive the lower suspension device 8. For this purpose, the lower surface 10 comprises for example one or more reception zones 14 of the lower suspension device 8 extending substantially parallel to the ground 6. According to the embodiment shown on the , the lower surface 10 comprises receiving zones 14 at the periphery of the lower surface 10 and these receiving zones 14 extend to a height greater than that of a central part of the lower surface 10.

The upper surface 12 is arranged to receive the upper support element 4, an upper suspension device 16, which will be described in more detail later, being interposed between the lower support element 2 and the upper support element 4. The upper surface 12 has a cradle shape adapted to accommodate the upper support element 4. For this purpose, in a transverse direction substantially perpendicular to the direction of elevation, and as more particularly visible on the , the upper surface 12 comprises a central part 18 extending substantially parallel to the ground 6 and two side parts 20 extending on either side of the central part 18. Each side part 20 extends between an integral lower end of the central part 18 and a free upper end, opposite the lower end. The side portions are inclined relative to the direction of elevation from their lower end so as to move away from each other. Thus, as shown in the , the distance between the lower ends of the side parts 20, measured in the transverse direction, is less than the distance between the upper ends of the side parts. The angle α formed between the direction of elevation and a lateral part 20 is for example substantially between 15° and 35°.

In a longitudinal direction, substantially perpendicular to the direction of elevation and the transverse direction, the upper surface 12 forms a groove open at its two ends, the central part 18 forming the bottom of the groove and the two lateral parts 20 forming the walls of it.

As shown on the , the upper suspension device 16 and the upper support element 4 are received in the groove formed by the upper surface 12 of the lower support element 2.

The upper support element 4 comprises a lower surface 22, facing the lower support element 2 and resting on the upper suspension device 16, and an upper surface 24, intended to receive the hull of the naval vessel, represented schematically by a mass 26 on the .

The lower surface 22 extends opposite the upper surface 12 of the lower support element 2 and has a shape similar to this in the transverse direction. Thus, the lower surface 22 comprises a central part 28 and two lateral parts 30 extending on either side of the central part 28. Under normal conditions of use of the tin 1, that is to say in the absence of particular stress on the lower 8 and upper 16 suspension devices, the central part 28 and the side parts 30 of the lower surface 22 are respectively substantially parallel to the central part 18 and to the side parts 20 of the upper surface 12 of the lower support element 2. Thus, the lateral parts 30 of the lower surface 22 are inclined and form an angle with the direction of elevation, substantially equal to the angle α.

The upper surface 24 connects the upper ends of the side parts 30 to each other in the transverse direction. Depending on the longitudinal direction, the upper surface 24 can have any shape adapted to the part of the hull of the naval vessel that the tin 1 must support. Thus, as shown in the , the upper surface 24 can have a substantially flat and horizontal shape, when the tin rests on a horizontal ground 6, with raised edges 32 in order to ensure maintenance in the longitudinal direction of the shell part received on the upper surface 24 .

Generally speaking, the lower suspension device 8 and the upper suspension device 16 are arranged to absorb external stresses on the upper support element 4 so that these stresses are not transmitted to the naval vessel supported by the coupling system. . The stresses are more particularly those generated following an earthquake whose effects are felt on the site where the naval vessel is in dry dock. Thus, the stresses damped by the suspension devices are for example significant vibrations or seismic tremors. These requests are transmitted by the ground 6 on which the tin 1 rests.

The lower suspension device 8 is arranged to absorb external stresses in directions substantially perpendicular to the direction of elevation Z, that is to say stresses in the direction of the ground 6. Thus, for a horizontal ground 6, the lower suspension device 8 is arranged to absorb horizontal external stresses on the tin 1. The lower suspension device 8 is in particular dimensioned so that the stresses transmitted by the tin 1 to the naval vessel are lower than those suffered in the event of an earthquake by the naval vessel when it is in the water.

The lower suspension device 8 comprises at least one lower suspension element 34, as shown in the , and preferably several lower suspension elements 34, as shown in Figs. 1 and 2.

Each lower suspension element 34 extends along an axis extending in the direction of elevation Z and comprises an absorption core 36 arranged to absorb external stresses. For this purpose, the absorption core 36 is for example formed of an elastomeric bearing with a lead core (known as Lead Rubber Bearing (LRB) in English). Thus, as shown in the , the absorption core 36 comprises a central cylinder 38 of lead surrounded by an elastomeric material 40, the axis of the central cylinder 38 extending in the direction of elevation Z. The elastomeric material 40 comprises a plurality of layers in elastomeric material 42, for example made of synthetic rubber, the layers of elastomeric material 42 being stacked on top of each other around the central cylinder 38 in the direction of elevation Z. The layers of elastomeric material, having substantially the shape of a disc , are for example laminated on top of each other. The layers of elastomer material 42 are reinforced by steel hoops. Such an absorption core 36 makes it possible to absorb energy in the event of an earthquake, this absorption being improved by the shearing of the central cylinder 38 by the steel hoops when the stresses propagate in the absorption core 36.

In the direction of elevation Z, the absorption core 36 is for example placed between a lower plate 44 and an upper plate 46 extending substantially perpendicular to the direction of elevation. Lower anchoring elements 48 extend for example projecting from the lower plate 44 towards the ground 6 in order to fix the lower suspension element 34 in the ground 6.

When the tin 1 comprises a single lower suspension element 34, feet 50 extend projecting from the upper plate 46, for example four feet 50, and ensure attachment between the lower suspension element 34 and the lower surface 10 of the lower support element 2. The feet 50 are fixed in the fixing zones 14 provided for this purpose on the lower surface 10.

According to a preferred embodiment, the lower suspension device 8 comprises four lower suspension elements 34 as shown in the . In this case, each lower suspension element 34 comprises an absorption core 36 as described above and a foot 50 extending between the absorption core 36 and the corresponding fixing zone 14 on the lower surface 10. The lower suspension elements 34 are distributed under the lower surface 10 of the lower support element 2. Thus, for four suspension elements 34, the fixing zones 14 are for example provided at the four corners of the lower surface 10. Each lower suspension element 34 may also comprise at least one lower anchoring element, not shown on the .

In the case where several lower absorption elements 34 are provided, each absorption core 36 has for example a natural frequency close to 0.5 Hz, for example between 0.4 Hz and 0.6 Hz. To do this , each absorption core has for example the following characteristics, the values varying depending on the characteristics of the naval vessel to be supported:

- shear modulus: 0.8 MPa

- diameter: between 500 mm and 800 mm

- thickness of the elastomer material: between 80 mm and 170 mm

- total height: between 200 mm and 400 mm

- maximum displacement in directions perpendicular to the direction of elevation: between 180 mm and 370 mm

- stiffness of the elastomeric material in the directions perpendicular to the direction of elevation: between 1.6 kN/mm and 1.7 kN/mm

- stiffness of the lead cylinder: between 16.0 kN/mm and 16.7 kN/mm

- effective stiffness: between 2.40 kN/mm and 2.60 kN/mm

- effective depreciation: between 25% and 30%

The upper suspension device 16 is arranged to absorb external stresses in the direction of elevation Z. Thus, for a horizontal floor 6, the upper suspension device is arranged to absorb vertical external stresses on the tin 1. The upper suspension device upper suspension 16 is notably dimensioned so that the stresses transmitted by the tin 1 to the naval vessel are lower than those suffered in the event of an earthquake by the naval vessel when it is in the water.

The upper suspension device 16 comprises at least one pair of upper suspension elements 52 extending on either side of the upper support element 4 in the transverse direction, as more particularly visible on the . Preferably, the upper suspension device 16 comprises a plurality of pairs of upper suspension elements 52.

The upper suspension elements 52 of a pair are inclined towards each other and each extend along an axis inclined with respect to the direction of elevation. More particularly, each suspension element 52 extends between an inclined part 20 of the upper surface 12 of the lower support element 2 and the inclined part 30 of the lower surface 22 of the upper support element 4, the parts inclined 20 and 30 extending substantially parallel as described above. As indicated previously, the upper suspension elements 52 of a pair extend on either side of the upper support element 4, that is to say the suspension elements extend between the parts inclined 20 and 30 on either side of the central parts 18 and 28 of the upper surface 12 of the lower support element 2 and of the lower surface 22 of the upper support element 4. The axis of each element upper suspension 52 forms an angle β with the direction of elevation Z, measured in the direction going from the upper support element 4 towards the lower support element 2 as shown in the . The angle β is for example substantially between 105° and 125°.

Each upper suspension element 52 is formed by an elastomeric bearing having substantially the shape of a cylinder of revolution, as visible on the . Such an elastomeric bearing is for example formed by a plurality of layers of elastomeric material, such as synthetic rubber, stacked one on top of the other along the axis of the upper suspension element 52. Such an elastomeric bearing is for example a high damping elastomeric insulator known by the English term High Damping Rubber Bearing (HDRB). Such a bearing is similar to the LRB used for the lower suspension element 34 except that it does not include a central lead cylinder.

Preferably, as shown in the , the upper suspension device 16 comprises several pairs of upper suspension elements 52, for example five pairs. The pairs are adjacent to each other in the longitudinal direction such that the upper support element 4 rests on upper suspension elements 52 substantially along its entire length, measured in the longitudinal direction.

When several pairs of upper suspension elements 52 are provided, each upper suspension element has for example a natural frequency close to 1.8 Hz, for example between 1.7 Hz and 1.9 Hz. To do this, each upper suspension element 52 has for example the following characteristics, the values varying depending on the characteristics of the naval vessel to be supported:

- shear modulus: 0.9 MPa

- diameter: between 300 mm and 450 mm

- thickness of the elastomer material: between 200 mm and 300 mm

- total height: between 300 mm and 400 mm

- maximum displacement depending on the direction of elevation: between 50 mm and 80 mm

- stiffness of the elastomeric material depending on the direction of elevation: between 7 kN/mm and 11 kN/mm

- effective depreciation: between 10% and 20%

In the event of an earthquake, shocks are transmitted by the ground to the pins 1 of the coupling system and first pass through the lower suspension device 8. The lower suspension element(s) 34 are then stressed and the different layers of material elastomer 42 absorb energy by moving relative to each other in directions perpendicular to the direction of elevation Z, the metal hoops further shearing the central cylinder 38. The lower suspension device thus absorbs external stresses according to directions perpendicular to the direction of elevations. The stresses are then transmitted to the upper support element 4 passing through the lower support element 2 and the upper suspension device 16. The upper suspension elements 52 absorb energy by compressing along their axis, this which makes it possible to absorb external stresses in the direction of elevation Z.

The securing system described above is particularly effective in reducing the effects of an earthquake on a naval vessel in dry dock supported by such a securing system. More particularly, such a rigging system can be used to support a nuclear-powered naval vessel, such as a submarine or a nuclear-powered surface ship. In fact, the pins of such a securing system are arranged so that the stresses transmitted by the pins to the naval vessel are lower than those experienced in the event of an earthquake by the naval vessel when it is in the water. Thus, it is not necessary to provide specific measures internal to the naval vessel so that it can withstand these stresses when it is not in the water, such measures leading to additional costs and increased complexity without bring particular benefit when the naval vessel is in the water.

Claims (10)

Rigging system for supporting a naval vessel in dry dock, comprising at least one tin (1) comprising a lower support element (2) resting on a floor (6) and an upper support element (4) intended supporting the naval vessel in a direction of elevation (Z), said tin (1) comprising at least one lower suspension device (8) and at least one upper suspension device (16), said lower support element (2 ) resting on the ground (6) via said lower suspension device (8) arranged to absorb external stresses on the tin (1) in directions substantially perpendicular to the direction of elevation (Z) and said element of upper support (4) resting on the lower support element (2) via said upper suspension device (16) arranged to absorb the stresses on the tin (1) in the direction of elevation (Z). Attraction system according to claim 1, in which the lower suspension device (8) comprises at least one lower suspension element (34) extending along an axis extending in the direction of elevation (Z). Attraction system according to claim 2, wherein the lower suspension element (34) comprises a central lead cylinder (38) surrounded by an elastomeric material (40), said central cylinder (38) extending along the The axis extending in the direction of elevation (Z). Attraction system according to claim 3, in which the elastomeric material (40) comprises a plurality of layers of elastomeric material (42) stacked one on top of the other in the direction of elevation (Z), said layers (42) being reinforced by steel frets. Attraction system according to any one of claims 2 to 4, in which the lower suspension device (8) comprises several lower suspension elements (34) distributed under a lower surface (10) of the lower support element ( 2), said lower surface (10) extending substantially parallel to the ground (6) and facing said ground (6). Attraction system according to any one of claims 1 to 5, in which the upper suspension device (16) comprises at least two upper suspension elements (52), extending on either side of the element upper support (4) in a transverse direction substantially perpendicular to the direction of elevation (Z), said upper suspension elements (52) being inclined towards each other and each extending along an inclined axis forming a non-zero angle (β) with the direction of elevation (Z), the angle (β) being measured in a direction going from the upper support element (4) towards the lower support element (2). Attraction system according to claim 6, in which the angle (β) between the inclined axis of each upper suspension element (52) and the direction of elevation (Z) is substantially between 105° and 125°. Attraction system according to claim 6 or 7, in which each upper suspension element (52) is an insulator made of high damping elastomeric material. A coupling system according to any one of claims 6 to 8, wherein the upper suspension device (16) comprises a plurality of pairs of upper suspension elements (52), said pairs being adjacent to each other in a longitudinal direction substantially perpendicular to the direction of elevation (Z) and to the transverse direction. Attachment system according to any one of claims 1 to 9, comprising a plurality of tins (1) spaced from each other at least in a main direction of the naval vessel to be supported by the attachment system.